Abstract:
The topography of the island nation of Sri Lanka is well shown in this
color-coded shaded relief map generated with digital elevation data from the
Shuttle Radar Topography Mission (SRTM).
Two visualization methods were combined to produce the image: shading and color
coding of topographic height. The shade image was derived by computing
topographic slope in the northwest-southeast direction, so
... that northwest
slopes appear bright and southeast slopes appear dark. Color coding is directly
related to topographic height, with green at the lower elevations, rising
through yellow and tan, to white at the highest elevations.
For this special view heights below 10 meters (33 feet) above sea level have
been colored red. These low coastal elevations extend 5 to 10 km (3.1 to 6.2
mi) inland on Sri Lanka and are especially vulnerable to flooding associated
with storm surges, rising sea level, or, as in the aftermath of the earthquake
of December 26, 2004, tsunami. These so-called tidal waves have occurred
numerous times in history and can be especially destructive, but with the
advent of the near-global SRTM elevation data planners can better predict which
areas are in the most danger and help develop mitigation plans in the event of
particular flood events.
Sri Lanka is shaped like a giant teardrop falling from the southern tip of the
vast Indian subcontinent. It is separated from India by the 50km (31mi) wide
Palk Strait, although there is a series of stepping-stone coral islets known as
Adam's Bridge that almost form a land bridge between the two countries. The
island is just 350km (217mi) long and only 180km (112mi) wide at its broadest,
and is about the same size as Ireland, West Virginia or Tasmania.
The southern half of the island is dominated by beautiful and rugged hill
country, and includes Mt Pidurutalagala, the island's highest point at 2524
meters (8281 ft). The entire northern half comprises a large plain extending
from the edge of the hill country to the Jaffna peninsula.
Elevation data used in this image were acquired by the Shuttle Radar Topography
Mission aboard the Space Shuttle Endeavour, launched on Feb. 11, 2000. SRTM
used the same radar instrument that comprised the Spaceborne Imaging
Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the
Space Shuttle Endeavour in 1994. SRTM was designed to collect 3-D measurements
of the Earth's surface. To collect the 3-D data, engineers added a 60-meter
(approximately 200-foot) mast, installed additional C-band and X-band antennas,
and improved tracking and navigation devices. The mission is a cooperative
project between NASA, the National Geospatial-Intelligence Agency (NGA) of the
U.S. Department of Defense and the German and Italian space agencies. It is
managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., for NASA's Earth
Science Enterprise,Washington, D.C. 
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